Cellular-based telephone connection system

ABSTRACT

An interface box links a user&#39;s cellular telephone with all the standard telephone extensions at the user&#39;s home or office. In this way, the portable cellular telephone is the interface between the user&#39;s telephone extensions and the telephone company. The interface box connects to the cellular telephone&#39;s access connector, for example, whenever the cellular telephone is laid in a cradle of the interface box. Through this connector is sent all power, signal and input/output connections. In addition to the interface circuitry, the interface box preferably recharges the cellular telephone&#39;s battery.

BACKGROUND OF THE INVENTION

Cellular telephones provide individuals the ability to always be incommunication with home or office even when traveling or commuting.Unfortunately, a person's cellular telephone number is different fromhis office or home number, so that he may not necessarily receive all ofthe telephone calls made to him. The regular telephone (i.e.,non-cellular telephone) at the user's home or office typically includesa number of extensions for convenience and efficiency, enabling the userto go to different rooms in the office or home and still receive hiscalls, or permit someone else to answer the calls or screen the callsfor the user. Therefore, the user typically de-activates his cellulartelephone upon arrival at a particular location (home or office).

A typical problem of a one-man office is that the individual may need togive his clients or customers as many as two or three telephone numberswhere he may be reached depending upon whether he is at home, at theoffice or in the car, for example. A customer or client may need to dialthree different telephone numbers before reaching the individual. Onefeature designed to at least somewhat ameliorate this problem is callforwarding. However, call forwarding is not a real solution because itmust be activated manually whenever the individual moves to anotherlocation and it must be deactivated manually when the individualreturns. If the individual forgets to do this, he will be completely outof communication. Moreover, while in transit, the individual willreceive no calls to the call-forwarded number until arriving at thecall-forwarded location.

The same problems arise in any situation in which an individual has morethan one location at which he must be reached at different times. Forexample, an individual may have a second home. More likely, anindividual may have more than one office, each office having a differenttelephone number. This latter case may apply to an individual with hisown business as well as a corporate employee who may need to work indifferent locations within a large office complex of the corporation.

SUMMARY OF THE DISCLOSURE

An interface box links a user's cellular telephone with all the standardtelephone extensions at the user's home or office. In this way, theportable cellular telephone is the interface between the user'stelephone extensions and the telephone company. The interface boxconnects to the cellular telephone's access connector, for example,whenever the cellular telephone is laid in a cradle of the interfacebox. Through this connector is sent all power, signal and input/outputconnections. In addition to the interface circuitry, the interface boxpreferably recharges the cellular telephone's battery.

Whenever the cellular telephone is thus connected to the interface box,each extension telephone at that location will act as though it werehard-wired to a normal telephone line. The extension telephones willlook and act, to the user, just like the telephone system found in mosthomes or small offices, for example. The multiple extensions will allring in response to an incoming call on the same telephone line.

With the invention, many locations frequented by the user (i.e.,different private offices, different corporate offices, second homes,etc.) may be provided with such an interface box, so that as the userarrives at a given location he puts his cellular telephone into theinterface box at that location, and upon departing he removes hiscellular telephone from the interface box and takes it with him. Thus,the telephone extension system at each location is activated with theuser's cellular telephone number as long as the user is there and isinactivated upon his departure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a pictorial schematic diagram illustrating a multipleextension telephone system embodying the invention.

FIG. 2 is a schematic diagram illustrating the connection of the systemof FIG. 1 to the telephone company network.

FIG. 3 is a schematic diagram illustrating a preferred embodiment of theinterface box employed in the system of FIG. 1.

FIG. 4 is a block diagram illustrating a first mode of the operation ofthe microprocessor in the interface box of FIG. 3.

FIG. 5 is a block diagram illustrating a second mode of the operation ofthe microprocessor in the interface box of FIG. 3.

FIG. 6 is a schematic diagram of a first alternative embodiment of theinvention.

FIG. 7 is a schematic diagram of a second alternative embodiment of theinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 1, fixed extension telephones 110, 115, 120, areconnected through standard in-house telephone wiring lines 125, 130, 135to an interface box or controller base 140. One of the extensiontelephones 110, 115, 120 may be replaced by a modem of the type used,for example, in a personal computer or facsimile machine. The controllerbase 140 has a cradle 145 which can receive a portable cellulartelephone 150. The controller base cradle 145 has a cellular telephoneconnector 155 with a conductor pattern that matches external connectorson the cellular telephone 150. This pattern varies depending upon themanufacturer and model of the cellular telephone 150. The connector 155can be transformed to conform to different connector patterns ofdifferent cell phone manufacturers or models by the use of differentmodular connector adapters (not shown in the drawings). Referring toFIG. 2, the cellular telephone 150 links the extension telephones 110,115, 120, through the controller base 140 to the telephone company ortelephone network 210 via the nearest cellular transmit/receive site220. As employed in this specification, the term “telephone company” andthe term “telephone network” both refer to the nationwide telephonesystem consisting primarily of local telephone company telephone wiringand long distance carrier microwave, fiber optic and wire links, as wellas to the international calling access this system provides.Communication between the portable cellular telephone 150 and thecellular site 220 is through radio propagation between the antenna 150 aof the cellular telephone 150 and the antenna 220 a of the cell site220. Multiple RJ-11 connectors are provided on the controller box 140 towhich the various extension telephones 110, 115, 120 may be connected.The extension telephones 110, 115, 120 all respond to incoming calls tothe telephone number of the portable cellular telephone 150, and makecalls on this same telephone number. FIG. 2 illustrates an alternativeembodiment of the controller base 140 in which the controller base 140has a single line connector and the fan-out from this connector tomultiple RJ-11 connectors in the house/office walls is providedexternally of the controller base 140, e.g., by in-house telephonewiring.

The internal structure of the interface box or controller base 40 isillustrated in FIG. 3. The controller base 140 provides the ringvoltage, tone signal and loop current necessary for the extensiontelephones 110, 115, 120 to function, in the manner of a conventionaltelephone line simulator of the type well-known in the art. For thispurpose, the controller base 140 includes three basic elements found ina telephone line simulator, namely a tone generator 310, a ringgenerator 315 and a current loop generator 320, all connected to acommon two-conductor standard telephone line bus 325. The telephone linebus is connected in common to plural external telephone jacks 327, whichare preferably RJ-11 connectors, to which the extension telephones or amodem may be connected. As in a conventional telephone line simulator,the current loop generator 320 provides a standard telephone on-hookline voltage (e.g., typically −20V to −48V), the tone generator 310provides the dial tone upon detecting an off-hook condition of anytelephone connected to the telephone line bus 325, while the ringgenerator generates the requisite voltage (e.g., typically 90 volts AC)to ring a telephone upon command (i.e., whenever an incoming call isreceived). Conventionally, an off-hook condition is detected by or forthe tone generator 310 by sensing a change in the line voltage from,typically, −48V to −10V due to a typical 20 mA current through thetelephone that has been taken off-hook. In addition to theseconventional elements, the controller base 140 further includes amicrocontroller 330 as well as the cellular telephone connectors 155referred to above with reference to FIG. 1. In a preferred embodiment ofthe invention, the microcontroller 330 controls the tone generator 310,the ring generator 315 and the current loop generator 320 in-response tosignals (e.g., digital codes) received from the cellular telephone 150.Furthermore, the microcontroller 330 responds to signals from theextension telephones 110, 115, 120 (e.g., off-hook line voltage drop,tone-dial numbers) to issue control commands to the cellular telephone150. These functions of the microcontroller 330 are discussed in detailbelow. The microcontroller 330 senses signals such as DTMF tones fromthe extension telephones 110, 115, 120 through an analog-to-digitalconversion interface 332 connected between the telephone line bus 325and the microcontroller 330. In one implementation, the microcontroller330 employs fast Fourier transforms to decode the DTMF frequencies, forexample, although the invention is not limited to such animplementation. The microcontroller 330 senses the off-hook and on-hookline voltages either through the analog-to-digital conversion interface332, or through conventional telephone interface circuitry of the typewell-known in the art (not shown in the drawing). In a preferredembodiment, the cellular telephone connector 155 includes an audio-inconnection 370, an audio-out connection 375, a digital-in connection 380and a digital-out connection 385. The cellular telephone connector 155may provide a path for both the audio-out connection 375 and theaudio-in connection 370 to the telephone line bus 325, with signalconditioning elements in the path which are discussed later in thisspecification. Alternatively, depending upon the design of theparticular cellular telephone, there may be only a single audioconnection, namely an audio-in/out connection, which the cellulartelephone connector therefore connects to the telephone line bus 325. Inaddition, the connector 155 includes positive, negative and/or groundbattery charging connectors 390 to charge the cellular telephone'srechargeable battery. A signal conditioner 395 adjusts the voltage andcurrent characteristics of the signals (e.g., the audio signals)received from the cellular telephone 150 for transmission to theextension telephones 110, 115, 120. It also adjusts the voltage andcurrent, characteristics of the signals (e.g., the audio signals)received from the extension telephones 110, 115, 120 for transmission tothe cellular telephone 150. These changes are necessary becausetypically the required voltage and current levels for audio signals sentor received by the cellular telephone 150 are different from those sentor received by the extension telephones 110, 115, 120. Such changes mayinclude not only changing voltage levels but also the removal of the DCline voltage (e.g., −48V) from the audio signal sent to the cellulartelephone 150 and removal of any ring voltage or AC dial tone signal orside tone, if necessary. The required changes in voltage and currentlevels to be performed by the signal conditioner 395 are determined byreferring to the manufacturer's specifications of the particularcellular telephone 150.

FIG. 4 illustrates the operation of the microcontroller 330 when atelephone call is made from one of the extension telephones 110, 115,120. The microcontroller 330 detects (e.g., through theanalog-to-digital converter 332) that one of the extension telephones110, 115, 120 is off-hook (block 405 of FIG. 4), and in responseactuates the tone generator 310 (block 410). Alternatively, the tonegenerator 310 itself may be sufficiently intelligent to appropriatelyactivate itself. More preferably, the microcontroller 330 is programmedto delay the activation of the tone generator 330 until themicrocontroller 330 detects that the cellular telephone has service oran RF carrier. As soon as the user begins dialing a number (e.g., byentering the number on a DTMF pad), the tone generator 310 isdeactivated by the microcontroller 330 or deactivates itself (block412). Thus, the tone generator 310 only generates a dial tone after anextension is taken off-hook and until the user begins dialing. Themicrocontroller 330 senses through the analog-to-digital converterdevice 332 a sequence of numbers corresponding to the DTMF tonesproduced as a user dials a telephone number on one of the extensiontelephones and stores the numbers as the number to be dialed (block415). (Alternatively, the DTMF tones may be sensed or decoded by meansother than the analog-to-digital converter device 332, such as aphase-locked loop, for example.) The microcontroller 330 preferably hasbeen programmed to recognize in accordance with conventional techniqueswhen a complete telephone number has been dialed or entered. Forexample, in the simplest but least preferred scheme, it would simplydetect that the user has stopped dialing after a pause of somepredetermined amount of time. More preferably, it may require entry of aparticular number of digits depending upon whether the number ispreceded by a 1 or a 0 or a 011, and so forth. After the microcontroller330 detects that a complete telephone number has been entered, themicrocontroller 330 sends the dialed telephone number on the digital outconnection 385 to the cellular telephone 150 (block 420) along with adigital “off-hook” or, equivalently, a “send” command (block 425). The“send” command causes the cellular telephone to go “off-hook” and dialthe number on the telephone network. At this point, the extensiontelephone functions as a normal telephone on the telephone network. Whenthe user hangs up the extension telephone, the microcontroller 330detects the return of the line voltage or current to the “on-hook” level(e.g., −20V to −48V typically) (block 430) and in response sends adigital “hang-up” (“end”) command on the digital out connection 385 tothe cellular telephone 150 (block 435).

FIG. 5 illustrates the operation of the microcontroller 330 when anincoming telephone call is made via the telephone network to thecellular telephone 150. The microcontroller 330 detects on the digitalin connection 380 a digital ring signal from the cellular telephone 150(block 505 of FIG. 5). In response, the microcontroller 330 activatesthe ring generator 315 (block 510). If the user then picks up one of theextension telephones 110, 115, 120, the microcontroller 330 detects anoff-hook condition (block 515), and responds by de-activating the ringgenerator 315 (block 520) and generating a digital “off-hook” command onthe digital out connection 385 (block 525) to the cellular telephone150. (This is like pushing the SEND button on a cellular phone when itrings.) During the ensuing telephone conversation, the audio signals arepassed back and forth for full audio duplex communication between thecellular telephone and the extension telephone (110, 115, 120) heldoff-hook by the user. As soon as the user hangs up the extensiontelephone, the microcontroller 330 detects an on-hook condition (block530) and the microcontroller 330 issues a digital “on-hook” commandhang-up) on the digital out connection 385 to the cellular telephone 150(block 535). The microcontroller is preferably programmed to respond toa digital indication from the cellular telephone that the incomingcaller has hung up or that the RF carrier to the cellular telephone hasbeen lost to re-activate the tone generator 310 to give the user a dialtone.

In summary, FIGS. 4 and 5 show that the portable cellular telephone 150is slaved by the base controller to the extension telephones so that thecellular telephone goes “on-hook” and “off-hook” in response to one ofthe extension telephones going on-hook and off-hook and dials a numberdialed by a user on one of the extension telephones. Moreover, the basecontroller renders the extension telephones responsive to the cellulartelephone in that they ring upon a call being received by the portablecellular telephone 150.

The microcontroller 330 performs the foregoing functions under thecontrol of internal firmware programmed in conventional manner inaccordance with the processes of FIGS. 4 and 5. Alternatively, themicrocontroller 330 may be dedicated logic programmed or “configured” ina conventional manner, e.g., in the manner of field programmable gatearrays, to perform the foregoing functions.

While the microcontroller 330 has been described as interpreting DTMFdial tones through the analog-to-digital converter 332, it may also beprogrammed to interpret pulse-dialing signals from the extensiontelephones through the analog-to-digital converter 332 or anothersuitable device using conventional techniques well-known in the art.

In addition to the digital signals received by the microcontroller onthe digital in connection 380 and the digital commands issued by themicrocontroller on the digital out connection 385, other signalsoptionally may be accommodated as well. For example, the microcontroller330 may receive from the cellular telephone 150, certain information fordisplay on an electronic display that may be provided on the controllerbase 140, for example. This information would be received on the digitalin line 380 and may include caller ID, signal strength, time, date,duration of call, and other information normally available from thecellular telephone 150.

Digital commands transmitted by the controller base 140 to the cellulartelephone 150 include those enumerated above and may additionallyinclude a digital mute command (so that the cellular telephone'smicrophone and speaker does not broadcast an on-going conversation), anda re-dial command. Moreover, if the cellular telephone 150 is highlysophisticated and has a memory and a menu of options, the commands mayalso include any or all of the commands required to operate the cellulartelephone's menu of options. For this purpose, either the controllerbase 140 or the extension telephones 110, 115, 120 would need thevarious keypad functions required to operate the cellular telephone'smenu (e.g., recall, AutoDial, telephone directory, forward, back, etc.,depending upon the manufacturer and model).

In other embodiments of the invention, the key elements of thecontroller base 140, such as the microcontroller 330 and thedigital-to-analog converter 332, may be placed inside a modified version150′ of the cellular telephone 150. For example, FIG. 6 illustrates suchan embodiment in which the tone generator 310, the ring generator 315and the current loop generator 320 are in the controller base 140 whilethe microcontroller 330 and the digital-to-analog converter 332 are bothon-board the modified cellular telephone 150′. In some cases, theconverter 332 may have both digital-to-analog conversion capability andanalog-to-digital conversion capability, each of which may be requireddepending upon the particular operation. In FIG. 6, the circuitrycomprising the standard cellular telephone 150 of FIG. 3 is contained inthe box labelled “cell phone circuitry” inside the modified cellulartelephone 150′ of FIG. 6. Furthermore, as illustrated in FIG. 7, more oreven possibly all of the active circuit elements within the controllerbase 140 of FIG. 3 may be placed instead inside the modified cellulartelephone 150′, leaving the telephone extension connectors 327 and thecellular telephone connector 155 on the controller base 140. In theembodiments of FIGS. 6 and 7, the cellular telephone connector 155includes a power connector (not shown in FIGS. 6 and 7) for furnishingelectrical power to the modified cellular telephone 150′ to charge itsbattery. In the embodiments of FIGS. 6 and 7, all of the connectionsillustrated in FIG. 3 are present, the difference being that many of theelements being connected reside inside the modified cellular telephone150′ rather than the controller base 140. For example, in thealternative embodiment of FIG. 6, the microcontroller 330 and thedigital-to-analog (and analog-to-digital) converter 332 and theconnections thereto are inside the modified cellular telephone 150′.Furthermore, in the alternative embodiment of FIG. 7, all of the activeelements as well as the connections thereto are inside the modifiedcellular telephone 150′.

While the invention has been described in detail by specific referenceto preferred embodiments, it is understood that variations andmodifications may be made without departing from the true spirit andscope of the invention.

What is claimed is:
 1. A base controller for linking extensiontelephones to a telephone network through a portable cellular telephone,said base controller comprising: an extension telephone connector forconnection to said external telephones; a telephone line simulatorconnected to the extension telephone connector; a cellular telephoneconnector for connecting to external connections provided on theportable cellular telephone, said cellular telephone connector includingan audio line connection coupled between said cellular telephone andsaid extension telephone connector to enable duplex voice communicationbetween the cellular telephone and the extension telephones; amicrocontroller responsive to the cellular telephone and responsive tothe extension telephones and programmed to cause at least one of: (a) aring signal to be generated by said telephone line simulator uponreceipt of a ring signal from said cellular telephone, (b) said cellulartelephone to connect and disconnect from the telephone network as saidextension telephones go off-hook and on-hook, (c) said cellulartelephone to dial a number dialed from one of said extension telephones;wherein said cellular telephone connector comprises a digital-inconnection for carrying command signals from the cellular telephone tosaid microcontroller, a digital-out connection for carrying commandsignals from said microcontroller to the cellular telephone, an audio inconnection for carrying audio signals from the cellular telephone tosaid extension telephone connector and an audio out connection forcarrying audio signals from said extension telephone connector to thecellular telephone.
 2. The base controller of claim 1 wherein saidmicrocontroller is programmed to cause each of (a), (b) and (c).
 3. Thebase controller of claim 1 further comprising a cradle for supportingthe portable cellular telephone, said cellular telephone connector beinglocated so as to contact said external connections on the portablecellular telephone whenever the cellular telephone is appropriatelyplaced in said cradle.
 4. The base controller of claim 3 wherein saidcellular telephone connector connects to a battery charging port of thecellular telephone.
 5. The base controller of claim 1 wherein saidtelephone line simulator comprises a current loop generator, a tonegenerator and a ring generator.
 6. The base controller of claim 5wherein said tone generator provides a dial tone to said telephoneextension connector upon one of said extensions being taken off-hook inthe absence of an incoming telephone call and prior to a number beingdialed on the one extension telephone.
 7. The base controller of claim 6wherein said microcontroller activates said ring generator upon receiptof a ring signal from the portable cellular telephone.
 8. The basecontroller of claim 1 further comprising signal condition circuitry forcoupling said audio-in and audio-out connections to said extensiontelephone connector.
 9. A method of coupling an internal telephone setto an external telephone network using a portable cellular telephonehaving access to the external telephone network, said method comprising:linking said portable cellular telephone to said internal telephone soas to enable full duplex audio communication between said internaltelephone set and said external telephone network via said cellulartelephone; controlling said portable cellular telephone to go on-hookand off-hook with said external telephone network in response to saidinternal telephone set going on-hook and off-hook respectively; whereinsaid cellular telephone connector comprises a digital-in connection forcarrying command signals from the cellular telephone to saidmicrocontroller, a digital-out connection for carrying command signalsfrom said microcontroller to the cellular telephone, an audio inconnection for carrying audio signals from the cellular telephone tosaid extension telephone connector and an audio out connection forcarrying audio signals from said extension telephone connector to thecellular telephone.
 10. The method of claim 9 further comprising:further controlling said portable cellular telephone to dial a number onsaid external telephone network after the number has been dialed on saidinternal telephone set.
 11. The method of claim 10 further comprising:controlling said internal telephone set to ring upon receipt of atelephone call from said external telephone network by said portablecellular telephone.
 12. A base controller comprising: a telephoneextension connector; a cellular telephone connector; a duplex audiosignal connection between said telephone extension connector and saidcellular telephone connector; and a microcontroller programmed togenerate off-hook and on-hook commands to said cellular telephoneconnector in response to off-hook and on-hook conditions sensed on saidtelephone extension connector; wherein said cellular telephone connectorcomprises a digital-in connection for carrying command signals from thecellular telephone to said microcontroller, a digital-out connection forcarrying command signals from said microcontroller to the cellulartelephone, an audio in connection for carrying audio signals from thecellular telephone to said extension telephone connector and an audioout connection for carrying audio signals from said extension telephoneconnector to the cellular telephone.
 13. The base controller of claim 12wherein: said microcontroller is further programmed to cause a ringsignal to be sent to said telephone extension connector in response to aring signal received via said cellular telephone connector.
 14. The basecontroller of claim 12 wherein: said microcontroller is furtherprogrammed to store a telephone number received from the telephoneextension connector and send the telephone number and a dial command tosaid cellular telephone connector.
 15. A single-number multi-locationtelephone system for use with an external telephone network, comprising:plural telephone sets at respective plural locations, each of saidplural telephone sets being independent; plural base controllers at saidrespective plural locations and individually connected to correspondingones of said telephone sets, each of said plural base controllers havinga cellular telephone connector through which said base controller linksthe corresponding telephone set to said external telephone networkthrough said cellular telephone connector; each of said plural basecontrollers comprising a microcontroller for slaving a portable cellulartelephone connected to said cellular telephone connector to thecorresponding telephone set; wherein said cellular telephone connectorcomprises a digital-in connection for carrying command signals from thecellular telephone to said microcontroller, a digital-out connection forcarrying command signals from said microcontroller to the cellulartelephone, an audio in connection for carrying audio signals from thecellular telephone to said extension telephone connector and an audioout connection for carrying audio signals from said extension telephoneconnector to the cellular telephone.
 16. The telephone system of claim15 wherein at least one of said telephone sets comprises pluralextension telephones connected to a common extension telephone wiringsystem of the corresponding location.
 17. The telephone system of claim16 wherein said one telephone set further comprises a modem. 18.Apparatus in which extension telephones are linked to a telephonenetwork through a portable cellular telephone, said apparatuscomprising: an extension telephone connector for connection to saidexternal telephones; telephone line simulator connected to the extensiontelephone connector; a cellular telephone connector for connecting toexternal connections provided on the portable cellular telephone, saidcellular telephone connector including an audio line connection coupledbetween the cellular telephone and said extension telephone connector toenable duplex voice communication between the cellular telephone and theextension telephones; said cellular telephone comprising: amicrocontroller responsive to the extension telephones and programmed tocause at least one of: (a) a ring signal to be generated by saidtelephone line simulator upon receipt of a ring signal from the cellulartelephone, (b) the cellular telephone to connect and disconnect from thetelephone network as the extension telephones go off-hook and on-hook,(c) the cellular telephone to dial a number dialed from one of theextension telephones.
 19. The apparatus of claim 18 wherein saidtelephone line simulator resides inside the cellular telephone.
 20. Theapparatus of claim 18 wherein said microcontroller is programmed tocause each of (a), (b) and (c).
 21. The apparatus of claim 18 furthercomprising a cradle for supporting the portable cellular telephone, saidcellular telephone connector being located so as to contact saidexternal connections on the portable cellular telephone whenever thecellular telephone is appropriately placed in said cradle.
 22. Theapparatus of claim 21 wherein said cellular telephone connector connectsto a battery charging port of the cellular telephone.
 23. The apparatusof claim 18 wherein said telephone line simulator comprises a currentloop generator, a tone generator and a ring generator.
 24. The apparatusof claim 23 wherein said tone generator provides a dial tone to saidtelephone extension connector upon one of the extension telephones beingtaken off-hook in the absence of an incoming telephone call and prior toa number being dialed on the one extension telephone.
 25. The apparatusof claim 24 wherein said microcontroller activates said ring generatorupon receipt of a ring signal from said portable cellular telephone. 26.The apparatus of claim 18 wherein said cellular telephone connectorcomprises an audio in connection for carrying audio signals from thecellular telephone to said extension telephone connector and an audioout connection for carrying audio signals from said extension telephoneconnector to the cellular telephone.
 27. The apparatus of claim 26further comprising signal condition circuitry for coupling said audio-inand audio-out connections to said extension telephone connector.